Thank you for the reference. I am not sure if Aaronson and I would agree. After all, depending on the situation, a philosopher of the kind I am talking about could claim that whatever progress has been made by answering the quesion Q' also allows us to know the answer to the question Q (maybe because they are really the same question), or at least to get closer to it, instead of simply saying that Q does not have an answer.

I think Protagoras' example of the question about whales being fish or not would make a good example of the former case.